Recently, studies on LTE (Long Term Evolution) have been in progress as Rel-8 specifications in 3GPP (3rd Generation Partnership Project) (for example, see non-patent document 1).
In this LTE, in order to enhance the efficiency of data transfer to a communication terminal, the communication quality of the downlink channel from the radio base station to the communication terminal is measured (calculated) by the communication terminal, and the result of measurement is transmitted (reported) as quality information CQI (Channel Quality Information) from the communication terminal to the radio base station.
Here, since LTE uses broadband, the system bandwidth is divided into multiple bands (subbands) and communication quality is measured for each subband and reported. This enables the radio base station to select resources of good communication quality and thereby perform efficient data transmission.
As described in non-patent document 1, for aperiodic CQI, the number of resource blocks per subband has been determined beforehand in accordance with the number of resource blocks in the entire system band. Here, the resource block is the unit of blocks into which radio resources are divided in a predetermined size.
FIG. 1 is a chart showing the correspondence between the number of resource blocks in the entire system band and the number of resource blocks per subband. This correspondence is the one that is disclosed in Table 7.2. 1-3 in non-patent document 1.
As shown in FIG. 1, the number of resource blocks in the entire system band and the number of resource blocks per subband are related beforehand. For example, when the number of resource blocks in the entire system band is 25, the number of resource blocks per subband is